This invention relates to can decorating apparatus and more particularly to can decorating apparatus with new and improved apparatus for applying a multiple-color decorative image to the cylindrical outer surface of a one-piece aluminum or steel can body member of a two-piece can assembly.
Decorators of this general type are described and shown in the following U.S. Pat. Nos., the disclosures of which are incorporated herein by reference: Sirvet 4,037,530; McMillin et al. 4,138,941; Dugan, et al. 4,222,479; Stirbis 4,267,771; Hahn 4,441,418; Stirbis 4,445,431; Stirbis 4,491,068; Stirbis 4,498,387; and Stirbis 4,509,555.
In general, decorator apparatus of this type comprises a rotatable mandrel wheel means for supporting can body embers on circumferentially spaced mandrel members; infeed means for loading undecorated can body members onto the mandrel members; a rotatable inking blanket wheel means having circumferentially spaced blanket segment members thereon for applying ink images to the can body members; a plurality of ink fountain means for holding a supply of ink of different colors; an ink transfer system associated with each ink fountain means including a plurality of circumferentially spaced ink stations each having an ink transfer roll members associated with each ink fountain means for transferring ink from the fountain means to a plate cylinder means and then to the blanket segment members; a transfer wheel means for receiving decorated can body members from the mandrel wheel means; a pin-chain means for receiving decorated can body members from the transfer wheel means and transferring the decorated can body members to a drying oven means. Such decorator apparatus is continuously operated by a motor means and a drive means with the various wheel means rotating synchronously. The construction and arrangement is such that each can body member is decorated along approximately 20 degrees of each 360 degree revolution of the mandrel wheel means when in contact with a blanket segment. Decorator apparatus of this type are operable between relatively low speeds of approximately 500 cans per minute and relatively high speeds of 1200 to 1400 or more cans per minute. In addition, such decorators may employ relatively few ink stations, e.g., 2 or 3 or may employ a relatively large number of multiple-color ink stations, e.g. 4 to 6, as illustrated by U.S. Pat. Nos. of Urban 3,996,851 and vander Griendt et al., 4,337,719.
In any event, a critical aspect of satisfactory operation is that each ink image derived from each separate ink station must be applied to the cylindrical surface of the blanket segments on the blanket wheel in a precise manner requiring the use of the proper amount and distribution of ink and proper alignment (i.e., registration) of the image relative to the blanket segment surfaces. Registration involves proper correlation of the image relative to the central longitudinal axis and circumference of the blanket segment members for transfer to the can body members as discussed in Stirbis, U.S. Pat. No. 4,491,068, the disclosure of which is incorporated herein by reference. The general term "registration" applies to both adjustment of alignment under static conditions when the decorator is not operating (running) and to dynamic conditions when the decorator is operating (i.e., "running registration" adjustment).
In the past, various ink transfer system registration adjustment mechanisms have been provided which have been generally relatively inaccurate, complicated, difficult to adjust and subject to misadjustment and misalignment during operation due to machine vibration and individual and tolerance variations of individual parts and cumulative tolerance variations of multiple parts. In general, misadjustment and misalignment can result from relative axial displacement and relative circumferential displacement and lack of parallelism of rotational axes between the various parts.
Proper alignment of the plate cylinder relative to the blanket wheel and blanket segment members is critical to obtaining a good ink image and to registration of the image with the can body members. In the past, the plate cylinder means and the ink transfer roll members for transferring ink from the fountain means to the plate cylinder means have been constructed and arranged as a sub-assembly unit whereby adjustment, misadjustment, replacement and/or removal of any one part affects the entire sub-assembly. Also, the drive systems for the ink transfer system have been constructed and arranged in a manner resulting in substantial vibration and application of forces tending to cause misalignment and malfunction of the plate cylinder means. Various prior art constructions and arrangements are shown in the following U.S. Pat. Nos. Brigham 3,223,028; Zurich 3,491,686; Szpitalak 3,786,747; Zurick 3,817,209; Skrypek 3,859,919; VanDer Roer 4,455,934; and Shirmizer 4,519,310.
In a can manufacturing line, prior art decorators have been responsible for as much as fifty percent of the scrap generated during operation of the can line. In addition, when frequent adjustments of registration are required, down-time of the can line is substantially increased. Some prior art decorators require that operation of the decorator be stopped in order to make registration adjustments. Other prior art decorators have employed apparatus intended to enable "running registration" adjustment but the adjustment apparatus has been relatively inaccurate and difficult to operate, and often unreliable and subject to relatively rapid loss of accuracy during operation. Another problem with prior art decorators has been the use of plate cylinder assemblies which are connected to the same drive system as the ink transfer rolls and are assembled and mounted as a unit including both the plate cylinder means and the ink transfer roll means. Thus, the plate cylinder means is subject to cumulative tolerance variations (slop) and vibration of the ink transfer roll system. Also, repair, maintenance, and replacement of parts of the plate cylinder and inker roll system often produces adverse effects on all parts of the unitary system requiring substantial down-time and readjustment of the entire alignment system.
The present invention provides a construction and arrangement to overcome the prior art problems relating to the ink station apparatus. The plate cylinder means for each status are each constructed, arranged, and mounted as a separate sub-assembly unit having new and improved alignment and registration means. The ink fountain means and ink transfer roll means for each station are also constructed as a separate sub-assembly unit having a separate support frame means. Each sub-assembly unit is precision-mounted on a single vertical frame plate means by special high precision mounting support means mounted in relatively non-critically dimensioned mounting holes and slots in the vertical frame plate means. New and improved alignment adjustment and mounting means are associated with the roll means and new and improved drive means are provided for separately driving the roll means and the plate cylinder means.
Each of the plate cylinder means are separately custom fitted and aligned on the vertical frame plate means with high precision during assembly at the factory. All of the plate cylinder means have separate drive gear means driven directly by the main bull gear which drives the blanket wheel and are mechanically separate from and independent of the ink roll system. Each plate cylinder means has an independent alignment and adjustment system which enables highly accurate alignment and adjustment both during assembly and during operation of the machine. Each of the ink transfer roll and fountain systems are separately constructed, assembled and mounted as a removable and replaceable unit. All of the roll-fountain units are of the same design and construction so as to be interchangeable at the various inking stations on the decorator. All of the roll-fountain units are separately driven by a separate timing belt-pulley drive system to substantially eliminate drive system vibration. Each roll-fountain unit has an independent separate alignment and adjustment system which enables highly accurate alignment and adjustment both before and during operation of the decorator. The apparatus is constructed and arranged to substantially eliminate misalignment problems due to tolerance variations of particular parts and accumulated total tolerance variations between parts which can result in axial and circumferential and parallelism misalignment problems due to "slop" between parts and "wobble" of parts. It is intended that the total tolerance variation be reduced to below 0.003 inch and preferably to 0.0005 inch or lower. Other advantages and improvements of apparatus and methods are described hereinafter.